I would like to use the Web Page Editor for my custom xml tags (for
example <mytags :button/>) with :
- a palette (similar to the one of HTML4.0) which allows the insertion of
my tags
- a preview (an HTML translation of my custom tags)

I dont use jsp or any other standard taglib but my custom xml tags
describe html like pages so I want to use this editor as it gives me an
html preview.

Which plug-ins should I consider looking at in order to be able to use
the wpe functionality for 'mytags ' namespace.

I have tried to define a new palette and elements in a definition xml file
(such as html_pi.xml) by extending the
org.eclipse.jst.jst.common.standardMetaDataFile plugin. What else should I
do to see my palette and be able to edit the file (without .tld in a web
project) ?

Is it completely the wrong way to approach the problem? Should I instead
define a new Content type such as the wst.html.core.htmlsource? If so,
what should I extend/subclass to avoid reinventing the wheel?